Film deposition method for producing a reaction product on a substrate

ABSTRACT

A film deposition method includes placing a substrate in a substrate receiving portion of a table provided in a vacuum chamber; and performing, at least once, a film deposition-alteration step and an alteration step. The film deposition-alteration step includes an adsorption step of allowing a first reaction gas to be adsorbed on an upper surface, a reaction product production step of allowing a second reaction gas and the first reaction gas adsorbed on the upper surface to react each other, thereby producing a reaction product, and an alteration process of allowing the upper surface to be exposed to plasma into which an alteration gas is activated. The first reaction gas is supplied from the first reaction gas supplying portion, the second reaction gas is supplied from the second reaction gas supplying portion, and the alteration is supplied from the plasma.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of and claims the benefitof priority under 35 U.S.C. 120 to U.S. patent application Ser. No.13/070,844 (Now U.S. Pat. No. 8,882,916), filed on Mar. 24, 2011, whichclaims the benefit of Japanese Patent Application No. 2010-075900 filedon Mar. 29, 2010 with the Japanese Patent Office, the entire contents ofwhich are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a film deposition apparatus and a filmdeposition method for depositing a film on a substrate in a vacuumchamber, and a computer readable storage medium storing a computerprogram for causing the film deposition apparatus to carry out the filmdeposition method.

2. Description of the Related Art

As a film deposition method for depositing a thin film on a surface of asubstrate such as a semiconductor wafer, there has been known aso-called Atomic Layer Deposition (ALD) or Molecular Layer Deposition(MLD), where a first reaction gas and a second reaction gas arealternately supplied to the substrate, thereby depositing an atomiclayer or a molecular layer of a reaction product. In such a filmdeposition method, when a film deposition temperature is low, forexample, organic substances in the reaction gases may be incorporatedinto the film as impurities. In order to remove such impurities, analteration process such as an annealing process and a plasma process maybe carried out.

However, because the plasma process can only alter properties of anextremely shallow portion of the thin film, the film cannot be uniformlyaltered in a film thickness direction when the plasma process is carriedout after the film deposition process is completed. In addition, when aplasma processing apparatus, which is provided separately from the filmdeposition apparatus, is used in order to carry out the plasma process,the substrate needs to be transferred from the film deposition apparatusto the plasma processing apparatus. Therefore, it takes a relativelylong time to carry out the film deposition and the plasma alteration.

Incidentally, there have been proposed so-called semi-batch type filmdeposition apparatuses where a film deposition process is carried out byrotating a susceptor, on which plural substrates are placed, withrespect to plural reaction gas supplying nozzles as disclosed in, forexample, Patent Documents 1 to 3 listed below. However, Patent Documents1 to 3 fail to provide concrete measures for solving the above problem.

Patent Document 1: U.S. Pat. No. 7,153,542 (FIGS. 8A, 8B).

Patent Document 2: Japanese Patent Publication No. 3144664 (FIGS. 1 and2, and claim 1).

Patent Document 3: U.S. Pat. No. 6,634,314.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above circumstances,and is directed to a film deposition apparatus, a film depositionmethod, and a computer readable storage medium storing a computerprogram that causes the film deposition apparatus to carry out the filmdeposition method, which realizes a thin film having uniform propertiesin a film thickness direction when film deposition is carried out byrotating a turntable, on which plural substrates are placed, withrespect to reaction gas supplying portions to produce plural layers ofthe reaction products of the reaction gases on the substrate.

According to a first aspect of the present invention, there is provideda film deposition apparatus comprising: a table that has a substratereceiving area on which a substrate is place and is provided in a vacuumchamber; a first reaction gas supplying portion that supplies a firstreaction gas to be adsorbed on an upper surface of the substrate to thesubstrate receiving area; a second reaction gas supplying portion thatsupplies a second reaction gas that reacts with the first reaction gasadsorbed on the upper surface of the substrate thereby to form areaction product to the substrate receiving area; a plasma generationportion that activates an alteration gas into plasma so that analteration process is carried out with respect to the reaction producton the substrate with the activated alteration gas; a rotation mechanismthat rotates the table relative to the first reaction gas supplyingportion, the second reaction gas supplying portion, and the plasmageneration portion; and a control portion that outputs a control signalso that the film deposition apparatus is caused to perform at leastonce, a film deposition-alteration step where the first reaction gas andthe second reaction gas are supplied to the substrate that is thenexposed to the alteration gas activated by the plasma, and an alterationstep where the alteration gas activated by the plasma is supplied to thesubstrate, while the first reaction gas is not supplied.

According to a second aspect of the present invention, there is provideda film deposition method comprising steps of: placing a substrate on asubstrate receiving portion of a table provided in a vacuum chamber; andperforming at least once a film deposition-alteration step and analteration step in this order, wherein in the film deposition-alterationstep, in order to perform a first reaction gas adsorption step thatallows a first reaction gas to be adsorbed on an upper surface of thesubstrate, a reaction product production step that allows a secondreaction gas and the first reaction gas adsorbed on the upper surface ofthe substrate to react each other, thereby producing a reaction product,and an alteration step that allows an alteration process to be performedwith respect to the reaction product with plasma into which analteration gas is activated, the table is rotated by a rotationmechanism relative to a first reaction gas supplying portion, a secondreaction gas supplying portion, and a plasma generation portion, whilethe first reaction gas is supplied from the first reaction gas supplyingportion, the second reaction gas is supplied from the second reactiongas supplying portion, and the alteration gas is supplied from theplasma, and wherein in the alteration step, the alteration gas activatedby the plasma is supplied to the substrate in the substrate receivingarea while the table is rotated, and the first reaction gas is notsupplied.

According to a third aspect of the present invention, there is provideda computer readable storage medium that stores a computer program to beused in a film deposition apparatus wherein a substrate is placed in asubstrate receiving area of a table provided in a vacuum chamber and acycle of alternately supplying at least two kinds of reaction gases tothe substrate is repeated plural times, the computer program comprisinginstruction steps that cause the film deposition apparatus to performthe film deposition method of the second aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view of a film deposition apparatusaccording to an embodiment of the present invention, taken along I-I′line in FIG. 3.

FIG. 2 is a perspective view schematically illustrating an innerconfiguration of the film deposition apparatus of FIG. 1.

FIG. 3 is a plan view schematically illustrating the film depositionapparatus of FIG. 1.

FIG. 4 is a vertical cross-sectional view schematically illustrating apart of the film deposition apparatus of FIG. 1.

FIG. 5 is an enlarged perspective view illustrating an example of anactivated gas injector.

FIG. 6 is a vertical cross-sectional view of the activated gas injectorof FIG. 5.

FIG. 7 is a vertical cross-sectional view illustrating a part of thefilm deposition apparatus, where the activated gas injector is provided.

FIG. 8 is a schematic view illustrating how a silicon oxide film ischemically altered according to an embodiment of the present invention.

FIG. 9 is a representation of an example of a gas supplying sequence ofa film deposition method according to an embodiment of the presentinvention.

FIG. 10 is another representation of the gas supplying sequence the filmdeposition method according to an embodiment of the present invention.

FIG. 11 is a schematic view illustrating a gas flow pattern of gases inthe film deposition apparatus of FIG. 1.

FIG. 12 is a graph illustrating results of experiments carried out inthe film deposition apparatus of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In embodiments of the present invention, the film deposition-alterationstep and the alteration step are carried out in this order. In the filmdeposition-alteration step, a film deposition process of allowing thesecond reaction gas to react the first reaction gas adsorbed on thesubstrate to form the reaction product, and then an alteration processof altering the reaction product with the plasma are performed byrotating the table on which the substrate(s) is placed relative to thefirst reaction gas supplying portion, the second reaction gas supplyingportion, and the plasma generation portion. In the alteration step, theother alteration process is performed by rotating the plasma generationportion relative to the table without supplying the first reaction gas.With this, a film having excellent uniformity and properties throughoutin the thickness direction can be obtained.

Referring to FIG. 1, which is a cut-away diagram taken along I-I′ linein FIG. 3, a film deposition apparatus according to an embodiment of thepresent invention is provided with a vacuum chamber 1 having a flattenedcylinder shape, and a turntable 2 that is located inside the chamber 1and has a rotation center at a center of the vacuum chamber 1. Thevacuum chamber 1 is made so that a ceiling plate 11 can be separatedfrom a chamber body 12. The ceiling plate 11 is pressed onto the chamberbody 12 via a ceiling member such as an O ring 13, so that the vacuumchamber 1 is hermetically sealed. On the other hand, the ceiling plate11 can be raised by a driving mechanism (not shown) when the ceilingplate 11 has to be removed from the chamber body 12.

The turntable 2 is rotatably fixed onto a cylindrically shaped coreportion 21. The core portion 21 is fixed on a top end of a rotationalshaft 22 that extends in a vertical direction. The rotational shaft 22penetrates a bottom portion 14 of the chamber body 12 and is fixed atthe lower end to a driving mechanism 23 that can rotate the rotationalshaft 22 clockwise, in this embodiment. The rotational shaft 22 and thedriving mechanism 23 are housed in a case body 20 having a cylinder witha bottom. The case body 20 is hermetically fixed to a bottom surface ofthe bottom portion 14 via a flanged pipe portion 20 a, which isolates aninner environment of the case body 20 from an outer environment.

As shown in FIGS. 2 and 3, plural (for example, five) circular concaveportions 24, each of which receives a semiconductor wafer (referred toas a wafer, hereinafter) W, are formed in a top surface of and along arotation direction (or a circumferential direction) of the turntable 2.Note that only one wafer W is illustrated in FIG. 3, for the sake ofillustration. Each of the concave portions 24 has a diameter slightlylarger, for example, by 4 mm than the diameter of the wafer W and adepth equal to a thickness of the wafer W. Therefore, when the wafer Wis placed in the concave portion 24, a surface of the wafer W is at thesame elevation of a surface of an area of the turntable 2, the areaexcluding the concave portions 24. In the bottom of the concave portion24 there are formed three through holes (not shown) through which threecorresponding elevation pins (not shown) are raised/lowered. Theelevation pins support a back surface of the wafer W and raises/lowersthe wafer W. The concave portions 24 are wafer W receiving areasprovided to position the wafers W and prevent the wafers W from beingthrown outwardly by centrifugal force caused by rotation of theturntable 2.

As shown in FIGS. 2 and 3, a first reaction gas nozzle 31, a secondreaction gas nozzle 32, and separation gas nozzles 41, 42, and aactivated gas injector 220, all of which may be formed of, for example,quartz, are arranged in radial directions and at predetermined angularintervals in the circumferential direction (or the rotation direction ofthe turntable 2). The nozzles 31, 32, 41, 42 oppose an area throughwhich the concave portions 24 of the turntable 2 pass. In theillustrated example, the activated gas injector 220, the separation gasnozzle 41, the first reaction gas nozzle 31, the separation gas nozzle42, and the second reaction gas nozzle 31 are arranged in this order ina clockwise direction (or the rotation direction of the turntable 2)from a transfer opening 15 (described later). The activated gas injector220 and the nozzles 31, 32, 41, 42 are introduced into the vacuumchamber 1 from an outer circumferential wall of the chamber body 12, inorder to extend along a radius direction of the chamber body 12 and tobe parallel with the turntable 2. Gas introduction ports 31 a, 32 a, 41a, 42 a serving as base ends of the corresponding nozzles 31, 32, 41, 42go through the outer circumferential wall of the chamber body 12. Thefirst reaction gas nozzle 31 and the second reaction gas nozzle 32 serveas a first reaction gas supplying portion and a second reaction gassupplying portion, respectively; and the separation gas nozzles 41, 42serve as a separation gas supplying portion. The activated gas injector220 is described later.

The reaction gas nozzle 31 is connected to a gas supplying source (notshown) of a first reaction gas containing silicon (Si) such as a bis(tertiary-butylamino) silane (BTBAS) gas, via a flow rate control valve(not shown). The reaction gas nozzle 32 is connected to a gas supplyingsource (not shown) of a second reaction gas such as ozone (O₃) gas oroxygen (O₂) gas, or the combination thereof, via a flow rate controlvalve (not shown). The separation gas nozzles 41, 42 are connected to agas supplying source (not shown) of nitrogen (N₂) gas serving as aseparation gas, via a flow rate control valve (not shown). Incidentally,the O₃ gas is used as the second reaction gas in the followingexplanation.

The reaction gas nozzles 31, 32 have plural ejection holes 33 opendownward to eject the corresponding source gases to the turntable 2. Theplural ejection holes 33 are arranged in longitudinal directions of thereaction gas nozzles 31, 32 at predetermined intervals of, for example10 mm. An area below the reaction gas nozzle 31 is a first process areaP1 in which the Si containing gas is adsorbed on the wafer W. An areabelow the reaction gas nozzle 32 is a second process area P2 in whichthe Si containing gas adsorbed on the wafer W is oxidized. The reactiongas nozzles 31, 32 are arranged away from a ceiling surface 45 and nearthe turntable 2 in the first and the second process areas P1, P2,respectively.

The separation nozzles 41, 42 are provided to form a separation area Dthat separates the first process area P1 and the second process area P2.In the separation area D, a convex portion 4 is provided on the lowersurface of the ceiling plate 11 of the vacuum chamber 1. The convexportion 4 has a top view shape of a sector whose apex is severed alongan arc line, and protrudes downward from the ceiling plate 11. An innerarc of the convex portion 4 is coupled with a protrusion portion 5(described later) and an outer arc of the convex portion 4 lies near andalong the inner circumferential surface of the chamber body 12 of thevacuum chamber 1. With the convex portion 4, the vacuum chamber 1 isdivided into plural areas in the circumferential direction. In addition,the separation gas nozzle 41 (42) is housed in a groove portion 43 thatis provided in such a manner that the groove portion 43 extends in theradial direction and substantially bisects the convex portion 4.

With the above configuration, there are flat low ceiling surfaces 44(first ceiling surfaces) on both sides of the separation gas nozzle 41(or 42), and high ceiling surfaces 45 (second ceiling surfaces) outsideof the corresponding low ceiling surfaces 44. The convex portion 4(ceiling surface 44) provides a separation space, which is a thin space,between the convex portion 4 and the turntable 2 in order to impede thefirst and the second gases from entering the thin space and from beingmixed.

Namely, taking for an example the separation area D where the separationgas nozzle 41 is provided, this separation area D impedes the secondreaction gas, which flows in the rotation direction of the turntable 2,from entering the thin space, and the first reaction gas, which flows ina direction opposite to the rotation direction of the turntable 2, fromentering the thin space. Incidentally, a noble gas such as argon (Ar)gas may be used as the separation gas, without being limited to thenitrogen gas.

In addition, the protrusion portion 5 is provided on the lower surfaceof the ceiling plate 11, as shown in FIG. 4. The protrusion portion 5 isprovided along the outer circumferential surface of the core portion 21in order to oppose the turntable 2 outside of the core portion 21. Theprotrusion portion 5 is formed to be continuous with the inner arc ofthe convex portion 4, in this embodiment, so that the lower surface ofthe protrusion portion 4 is at the same level as that of the convexportion 4 (or the ceiling surface 44).

Incidentally, FIGS. 2 and 3 are a perspective view and a top view thatillustrate the inside of the chamber body 12, where the chamber body 12is horizontally severed at the level that is lower than the ceilingsurface 45 and higher than the separation gas nozzles 41, 42, for thesake of convenience.

As stated above, there are the ceiling surfaces 44 and the ceilingsurfaces 45 that is higher than the ceiling surface 44 that arealternately arranged in the circumferential direction of the chamberbody 12. FIG. 1 is a vertical cross-sectional view of an area where theceiling surfaces 45 are provided; and FIG. 4 is a verticalcross-sectional view of an area where the ceiling surfaces 44 areprovided. In a circumferential portion of the sector-shaped convexportion 4 (or an outer circumferential portion facing the inner surfaceof the chamber body 12), there is provided a bent portion 46 that bendsin an L-shape. The bent portion 46 opposes the outer circumferentialsurface of the turntable 2 as shown in FIGS. 2 and 4. The bent portion46 impedes the reaction gases from entering the separation area D fromthe both sides of the separation area D and from being mixed. Becausethe convex portion 4 is attached on the lower surface of the ceilingplate 11, and thus the convex portion 4 can be removed from the chamberbody 12, there needs to be gaps between the outer circumferentialsurface of the turntable 2 and the inner circumferential surface of thebent portion 46 and between the outer circumferential surface of thebent portion 46 and the inner circumferential surface of the chamberbody 12. These gaps may be as narrow as the height of the ceilingsurface 44 with respect to the turntable 2, for example.

A circumferential wall of the chamber body 12 has a vertical inner wallthat is close to the outer circumferential surface of the bent portion46 in the separation area D, as shown in FIG. 4. On the other hand, thecircumferential wall is indented outward in areas that do not correspondto the separation areas D, as shown in FIG. 1, so that there is arelatively large space with respect to the outer circumferential surfaceof the turntable 2 and from the bottom of the chamber body 12 up to theouter circumferential surface of the turntable 2. For the sake of thefollowing explanation, the space having substantially a box shape isreferred to as an evacuation area. Specifically, the evacuation area ingaseous communication with the first process area P1 is referred to as afirst evacuation area E1, and the evacuation area in gaseouscommunication with the second process area P2 is referred to a secondevacuation area E2, hereinafter. At the bottoms of the first and thesecond evacuation areas E1, E2, a first evacuation port 61 and a secondevacuation port 62 are formed, respectively, as shown in FIGS. 1 and 3.The first and the second evacuation ports 61, 62 are connected to avacuum pump 64 serving as an evacuation unit via an evacuation pipe 63,as shown in FIG. 1. A reference symbol 65 in FIG. 1 represents apressure controller.

As shown in FIGS. 1 and 4, a heater unit 7 serving as a heating portionis provided in a space between the bottom portion 14 of the chamber body12 and the turntable 2, so that the wafers W placed on the turntable 2can be heated through the turntable 2 at a determined temperature, forexample 450° C., which is determined by a process recipe. In addition, aring-shaped cover member 71 is provided beneath the turntable 2 and nearthe outer circumference of the turntable 2 in order to surround theheater unit 7, so that the space where the heater unit 7 is placed ispartitioned from the outside area of the block member 71, therebyimpeding the gas from entering the space below the turntable 2. Thecover member 71 includes an inner member 71 a provided to face the outercircumferential portion of the turntable 2 and an area outside of theturntable 2 from below, and an outer member 71 b provided between theinner member 71 a and the inner circumferential surface of the chamberbody 12. The outer member 71 b is severed in part in order to leavespaces above the evacuation ports 61, 62, thereby allowing a space abovethe turntable 2 to be in gaseous communication with the evacuation ports61, 62. In addition, the upper surface of the outer member 71 b comesclose to the bent portion 46. In other words, the cover member 71includes the outer member 71 b provided to come close to the bentportion 46 in an area below the bent portion 46 formed at the outercircumferential portion of the convex portion 4, and the inner member 71a that is provided below the outer circumferential portion of theturntable 2 and surrounds the heater unit 7.

A protrusion portion 14 that comes close to the lower surface of thecore portion 21 is provided inside the space where the heater unit 7 ishoused (or in an area closer to the rotation center of the turntable 2than the space where the heater unit 7 is housed) in the bottom portion14, leaving a narrow space between the protrusion portion 14 and thecore portion 21. In addition, there is another narrow space between acenter hole through which the rotational shaft 22 passes and therotational shaft 22, and this narrow space is in gaseous communicationwith the case body 20. A purge gas supplying pipe 72 is connected to anupper portion of the case body 20. Moreover, plural purge gas supplyingpipes 73 are connected at predetermined angular intervals to areas belowthe heater unit 7 in order to purge the space where the heater unit 7 ishoused. A cover member 7 a, which may be formed of, for example, quartzglass, is supported by the upper surface of the inner member 71 and theupper portion of the protrusion portion 12 a, so that the heater unit 7is covered by the cover member 7 a and thus gases are substantiallyprevented from entering the space where the heater unit 7 is housed.

Referring to FIGS. 1 and 4, a separation gas supplying pipe 51 isconnected to the top center portion of the ceiling plate 11 of thechamber 1, so that N₂ gas is supplied as a separation gas to a space 52between the ceiling plate 11 and the core portion 21. The separation gassupplied to the space 52 flows through the thin gap 50 between theprotrusion portion 5 and the turntable 2 and then along the top surfaceof the turntable 2. Because the space surrounded by the protrusionportion 5 is filled with the N₂ gas, the reaction gases (BTBAS, O₃)cannot be mixed between the first process area P1 and the second processarea P2 through the center portion of the turntable 2.

FIGS. 2 and 3 show a transport opening 15 through which the wafer W istransferred into or out from the vacuum chamber 1 by a transfer arm 10(see FIG. 3). The transfer opening 15 is provided with a gate valve (notshown) by which the transfer opening 15 is opened or closed. Because thewafer W is transferred into the vacuum chamber 1 through the transferopening 15 and placed in the concave portion 24 in the turntable 2, liftpins and an elevation mechanism (not shown) are provided in areacorresponding to the transfer opening 16 below the turntable 2. The liftpins can move upward/downward through corresponding through-holes (notshown) formed in the turntable 24, so that the wafer W is transferredbetween the transfer arm 10 and the concave portion 24 of the turntable2.

Next, the activated gas injector 220 is described. The activated gasinjector 220 is arranged to generate plasma in an area above theturntable 2 and along the radius direction of the turntable 2, so thatthe entire surface of the wafer W placed in the concave portion 24 canbe exposed to the plasma. The activated gas injector 220 is to alterproperties of a silicon oxide film deposited on the wafer W throughreaction of the Si containing-gas and the O₃ gas every rotation of theturntable 2. In order to introduce a property alteration gas to beactivated by the plasma, the activated gas injector 220 is provided witha gas introduction nozzle 34 serving as a property alteration gassupplying portion, as shown in FIGS. 5 and 6. The gas activation nozzle34 may be made of, for example, quartz glass. In addition, the activatedgas injector 220 has a plasma generation member composed of a pair ofsheath pipes 35 a, 35 b located downstream relative to the rotationdirection of the turntable 2 in relation to the gas introduction nozzle34. The plasma generation member 80 generates the plasma that activatesthe property alteration gas supplied from the gas introduction nozzle34. The sheath pipes 35 a, 35 b have a rod shape and are parallel witheach other. In the illustrated example, two plasma generation members 80having the same length are provided to be parallel with each other. Inother embodiments, three or more plasma generation members 80 may beprovided.

The gas introduction nozzle 34 and the plasma generation members 80, 80go through the circumferential wall of the chamber body 12 in anair-tight manner, and are arranged to be parallel with the turntable 2(and thus the wafer W in the concave portion 24) along the tangentialdirection to the rotation direction of the turntable 2. In addition, thegas introduction nozzle 34 and the plasma generation members 80, 80 aresupported by their base end portion 80 a fixed in the circumferentialwall of the chamber body 12. Reference symbols 341 in FIG. 6 representplural gas holes provided along the longitudinal direction of the gasintroduction nozzle 34.

As shown in FIG. 3, one end of a plasma gas line 251 that supplies theproperty alteration gas, for example, O₂ gas, to be activated intoplasma is connected to the gas introduction nozzle 34, and the other endof the plasma gas line 251 is connected to a plasma gas supplying source254 that stores the property alteration gas through a valve 252 and aflow rate controller 253. As the property alteration gas, a noble gassuch as argon (Ar) gas and helium (He) gas may be used instead of or inaddition to the O₂ gas. The sheath pipes 35 a, 35 b in each of theplasma generation members 80, 80 may be made of, for example, quartzglass, alumina (aluminum oxide), or yttria (yttrium oxide, Y₂O₃). Inaddition, electrodes 36 a, 36 b, which may be made of, for example,nickel alloy or titanium, are inserted into the corresponding sheathpipes 35 a, 35 b, as shown in FIG. 6, thereby constituting parallelelectrodes. High frequency electric power having a frequency of, forexample, 13.56 MHz is applied at, for example, 500 W across theelectrodes 36 a, 36 b from a high frequency supplying source 224 througha matching box 225. Reference symbols 37 in FIG. 6 represent protectionpipes connected to a base end side of the sheath pipes 35 a, 35 b (or inthe side of the inner circumferential surface of the chamber body 12).The protection pipes 37 are omitted in FIG. 5 or the like. In addition,the sheath pipes 35 a, 35 b are omitted in drawings except for FIG. 6.

A reference symbol 221 in FIG. 5 represents a cover body that isarranged to cover a top side and four side areas (both sides along thelong and short edges) of a space where the gas introduction nozzle 34and the sheath pipes 35 a, 35 b are provided. The cover body 221 may bemade, for example, an insulating material or quartz glass. In addition,reference symbols 222 in FIG. 5 represent flow limiting surfaces thatextend in a flange shape in a horizontal direction. Specifically, theflow limiting surfaces 222 are provided from one end through the otherend of the cover body 221 along the longitudinal direction of the coverbody 21 and extend outward from the corresponding lower edge portions ofthe cover body 221. According to the flow limiting surfaces 222, thegases such as the O₃ gas and the N₂ gas flowing along the rotationdirection of the turntable 2 over the upper surface of the turntable 2are impeded from entering the inside of the cover member 221. Inaddition, the flow limiting surfaces 222 are arranged close to the uppersurface of the turntable 2 so that a gap t between the flow limitingsurface 222 and the upper surface of the turntable 2 is small enough toefficiently impede the gases from entering the inside of the cover body221. Moreover, the flow limiting surface 222 has a width u that becomeswider in the rotation direction of the turntable 2 along a directiontoward the inner circumferential surface of the chamber body 12. Notethat the gases in the vacuum chamber 1 flow faster in an outer area thanan inner area of the vacuum chamber 1 because of the rotation of theturntable 2. Therefore, the flow limiting surface 222 that becomes widertoward the outer area of the vacuum chamber 1 is advantageous to impedethe gases flowing in the outer area from entering the inside the coverbody 222. Reference symbols 223 in FIG. 7 represent supporting membersprovided between the cover body 221 and the ceiling plate 11 of thevacuum chamber 1 in order to support the cover body 221 from the ceilingplate 11. The supporting members 223 are simplified in FIG. 7, for thesake of convenience.

In addition, the film deposition apparatus according to this embodimentis provided with a control portion 100, which is made of a computer, forcontrolling entire operations of the film deposition apparatus. Thecontrol portion 100 includes a memory portion 101 (see FIG. 1) thatstores a computer program that causes the film deposition apparatus tocarry out a film deposition method including a filmdeposition-alteration step (a first step) where the film deposition andthe property alteration are carried out during one rotation of theturntable 2, and an alteration step (a second step) where only theproperty alteration is carried out during one rotation of the turntable2. The first and the second steps are carried out in this order. Inaddition, the memory portion 101 stores a time ratio (T1/T2) of thefirst step and the second step, a total time (T1+T2) of the first stepand the second step, and the number of cycles of the first step and thesecond step, where the T1 represents a step time of the first step andT2 represents a step time of the second step. The computer programincludes a group of instructions that causes the film depositionapparatus to carry out the film deposition method. The computer programmay be stored in a computer readable storing medium 102 (see FIG. 1)such as a hard disk, a compact disk, a magneto-optical disk, a memorycard, and a flexible disk, and downloaded to the memory portion 102 andfurther to the control portion 100.

Next, the operations of the film deposition apparatus according to thisembodiment (film deposition method) are described in the following.First, one of the concave portions 24 of the turntable is in alignmentwith the transfer opening 15 by appropriately rotating the turntable 2.Next, the gate valve (not shown) is opened, and the wafer W istransferred into the vacuum chamber 1 through the transfer opening 15 bythe transfer arm 10 and is placed in the concave portion 24 of theturntable 2 by the lift pins (not shown) and the transfer arm 10 thatcooperatively operate. Such operations are intermittently repeated sothat five wafers W are placed in the corresponding concave portions 24of the turntable 2.

Next, after the transfer arm 10 recedes from the vacuum chamber 1, thegate valve (not shown) is closed and the vacuum chamber 1 is evacuatedto the reachable lowest pressure by the vacuum pump 64. Then, the N₂ gasis supplied at predetermined flow rates from the separation gas nozzles41, 42, the separation gas supplying pipe 51, and the purge gassupplying pipes 72. Along with this, the inside space of the vacuumchamber 1 is maintained at a predetermined pressure by the pressurecontroller 65. Next, the turntable 2 starts rotating in a clockwisedirection at a rotational speed of, for example, 20 revolutions perminute (rpm), and the wafer W is heated at, for example, 450° C. by theheater unit 7.

Subsequently, the Si containing gas is supplied from the reaction gasnozzle 31; the O₃ gas is supplied from the reaction gas nozzle 32; theO₂ gas is supplied at, for example, 5 standard liters per minute (slm)from the gas introduction nozzle 34; and the high frequency electricpower having a frequency of 13.56 MHz is applied across the sheath pipes35 a, 35 b (the electrodes 36 a, 36 b).

In this case, the O₂ gas ejected from the gas introduction nozzle 34toward the sheath pipes 35 a, 35 b through the plural gas holes 341 isactivated by the high frequency electric power applied across the sheathpipes 35 a, 35 b to generate plasma including, for example, oxygen ions,oxygen radicals, or the like in the activated gas injector 220. Thisplasma (activated species) moves downward from the activated gasinjector 220 toward the wafer W that rotates along with the turntable 2.

On the other hand, the Si containing gas is adsorbed on the uppersurface of the wafer W in the first process area P1, and the Sicontaining gas adsorbed on the upper surface of the wafer W is oxidizedby the O₃ gas in the second process area P2, thereby producing amolecular layer(s) of the silicon oxide. In this silicon oxide layer(s),impurities such as moisture (or OH group) and organic substances may beincorporated from groups of the Si containing gas. When the wafer Wreaches an alteration area 150, which is below the activated gasinjector 220, the silicon oxide layer(s) is altered by the plasma.Specifically, the impurities are removed from the silicon layer(s) orthe silicon atoms and the silicon atoms are re-arranged when the uppersurface of the wafer W (or the silicon layer(s) formed on the wafer W)is exposed by the plasma or bombarded by active species in the plasma,as schematically shown in FIG. 8(a). Therefore, the silicon layer(s) ispurified and becomes densified. When the turntable 2 is rotated twoturns, or the film deposition-alteration step including the filmdeposition process and the alteration process is carried out for sixseconds, a silicon oxide layer having a film thickness of 0.25 nm isproduced on the upper surface of the wafer W.

Incidentally, depending on flow rates of the reaction gases, a filmthickness of the reaction product per one cycle of the film depositionprocess (per one rotation of the turntable 2), a rotational speed of theturntable 2, or the like, the above alteration of the reaction productmay not be sufficiently carried out. Namely, the reaction product formedon the upper surface of the wafer W may still have impurities or maystill be insufficiently densified in the film deposition-alterationstep. Therefore, the alteration step is carried out in order tosufficiently alter the reaction product formed on the upper surface ofthe wafer W in the film deposition-alteration step.

Specifically, while the flow rates of the gases from the second reactiongas nozzle 32, the gas introduction nozzle 34, the separation gasnozzles 41, 42, and the supplying pipes 51, 72 are maintained the sameas in the film deposition-alteration step by the control portion 100,supplying the Si containing gas from the first reaction gas nozzle 31 isterminated. In this case, because the flow rate of the Si containing gasat the film deposition-alteration step is smaller than those of the O₃gas and the separation gas, a pressure in the vacuum chamber 1 is notsignificantly changed when the process steps change from the filmdeposition-alteration step to the alteration step (or when the supplyingthe Si containing gas is terminated).

When the Si containing gas is not supplied, the Si containing gas israpidly evacuated from the vacuum chamber 1 in such a manner that theseparation gases push the Si containing gas in the vacuum chamber 1toward the evacuation port 61. In addition, the Si containing gasremaining in the reaction gas nozzle 31 is also evacuated from theevacuation port 61. In this case, it may be said that the first processarea 1 is not created in the vacuum chamber 1 at the alteration step.Therefore, the wafer W passes through the second process area P2 and thealteration area 150 in this order because of rotation of the turntable2.

In the second process area P2, the reaction product is not adverselyaffected when the reaction product on the upper surface of the wafer Whas been already oxidized. On the other hand, the alteration process iscarried out in the alteration area 150, so that the impurities areremoved from the reaction product, and the silicon and oxide atoms arerearranged. When the turntable 2 is rotated six turns (for example, 18seconds) in such a manner, the reaction product on the upper surface ofthe wafer W is exposed to the plasma. Therefore, the reaction product onthe upper surface of the wafer W is altered to a greater degree in thealteration step than in the film deposition-alteration step. Inaddition, the reaction product on the upper surface of the wafer W issufficiently thin after the film deposition-alteration step so that thereaction product is uniformly altered in the film thickness direction.

Namely, because the rearrangement of the atoms takes place in a vertical(film thickness) direction (or between an Nth layer and an (N+1)thlayer), the reaction product having uniform properties in the filmthickness direction. In this case, assuming that step times of the filmdeposition-alteration step and the alteration step are T1 and T2,respectively, the process step time ratio (T1/T2) is 1/3 (6/18 seconds).In addition, the total step time (T1+T2) is 24 seconds (6+18 seconds).In this case, while the Si containing gas is intermittently supplied,the O₃ gas and the plasma (O₂ gas) are continuously supplied at the sameflow rates throughout plural process cycles, as shown in FIG. 9. Inother words, the wafer W is exposed to the Si containing gas, the O₃gas, and the plasma plural times in this order in the filmdeposition-alteration step, and to the O₃ gas and the plasma pluraltimes in this order (without the Si containing gas) in the alterationstep, as shown in FIG. 10.

When the process cycles are repeated plural times (for example, 40times), the reaction product layer(s), which has been altered, isformed, and thus the thin film having improved and uniform filmproperties is deposited on the wafer W. Because the five wafers W areplaced along the circumferential direction on the turntable 2, when thefilm deposition-alteration step is initiated, the wafer W may be exposedto the O₃ gas or the plasma before the Si containing gas. In addition,when the process steps are switched from the film deposition-alterationstep to the alteration step after only a part of the upper surface ofthe wafer W has been exposed to the Si containing gas, the remainingpart of the wafer W is not exposed to the Si containing gas. In thesecases, there may be thickness variations in the same wafer W or betweenthe wafers W. However, because the process cycles are repeated pluraltimes, such variations become less significant. Therefore, the thinfilms having improved and uniform film properties can be obtained.

Because the separation area D is not provided between the activated gasinjector 220 and the second reaction gas injector 32 in the vacuumchamber 1, the O₃ gas and the separation gas (N₂ gas) flows toward theactivated gas injector 220 from the upstream side of the activated gasinjector 220 because of rotation of the turntable 2. However, such gasesare least likely to flow through the space between the activated gasinjector 220 and the turntable 2. This is because the cover body 221 isarranged closer to the upper surface of the turntable 2, leaving thenarrow gap t between the flow limiting surface 222 and the turntable 2and a wider area above the cover body 221. In addition, another reasonis that a pressure is higher in the inside of the cover body 221 than inthe outside of the cover body 221 because the alteration gas is suppliedto the inside of the cover body 221 from the gas introduction nozzle 34.

In addition, because the flow limiting surface 222 has the width u thatbecomes greater toward the outer circumference of the turntable 2, thegases flowing toward the activated gas injector 220 from the upstreamside of the activated gas injector 220 can rarely flow into the insideof the cover body 221 even when the gases flow faster in an area nearthe outer circumference of the turntable 2. Therefore, the gases flowingtoward the activated gas injector 220 from the upstream side of theactivated gas injector 220 flow above the activated gas injector 222 andinto the evacuation port 62, as shown in FIG. 6. Accordingly, becausethe O₃ gas and the N₂ gas are not influenced by the high frequencyelectric power, NO_(x), for example, is not generated and thus the innersurface of the vacuum chamber 1 or members in the vacuum chamber 1 areless likely to be corroded by the NO_(x). In addition, the wafers W arerarely influenced by the NO_(x). Incidentally, the impurities that areremoved from the silicon oxide by the alteration process may become gasand thus evacuated along with the O₃ gas, O₂ gas, and N₂ gas through theevacuation port 62.

In addition, because the N₂ gas serving as the separation gas issupplied in an area between the first process area P1 and the secondprocess area P2 and the N₂ serving as the separation gas is suppliedfrom the center area C, the Si containing gas and the O₃ gas areevacuated from the corresponding evacuation ports 61, 62 in the filmdeposition-alteration step, as shown in FIG. 11.

Moreover, because the inner circumferential surface of thecircumferential wall of the chamber body 12 is indented outward in anarea below the high ceiling surface 45 below which the reaction gasnozzles 31, 32 and the activated gas injector 220 are arranged, so thatthe evacuation areas E are created, and the evacuation ports 61, 62 areformed below the evacuation areas E, a pressure in the area below thehigh ceiling surface 45 is lower than a pressure in the thin area belowthe ceiling surface 44 and the center area C.

Incidentally, because the area below the turntable 2 is purged with theN₂ gas, the gases that have reached the evacuation area E are lesslikely to flow into the first process area P1 or the second process areaP2 through the area below the turntable 2.

An example of process parameters preferable in the film depositionapparatus according to this embodiment is listed in the following. Arotational speed of the turntable 2 is 1 through 500 rpm (in the case ofthe wafer W having a diameter of 300 mm); a pressure in the vacuumchamber 1 is about 1.067 kPa (8 Torr); a flow rate of the Si containinggas is 100 sccm; a flow rate of the O₃ gas is about 10000 sccm; a flowrate of the N₂ gas from the separation gas nozzles 41, 42 is about 20000sccm; and a flow rate of the N₂ gas from the separation gas supplyingpipe 51 at the center of the vacuum chamber 1 is about 5000 sccm. Inaddition, the number of cycles of alternately supplying the reactiongases to the wafers W is, for example about 1000, though changesdepending on the film thickness required.

In this embodiment, after the film deposition-alteration process thatincludes the film deposition process where the silicon oxide film isformed by adsorbing the Si containing gas on the upper surface of thewafer W, and supplying the O₃ gas thereby to oxidize the Si containinggas on the upper surface of the wafer W into the silicon oxide, and theproperty alteration process where the silicon oxide is altered by usingthe plasma, the property alteration process is carried out that altersthe silicon oxide on the wafer W without supplying the Si containinggas. Therefore, the thin film having uniform and improved filmproperties in the film thickness direction can be obtained. In addition,the step time ratio (T1/T2) and the total step time (T1+T2) may bechanged so that a degree of alteration can be adjusted in a wider range.For example, when the number of cycles of film deposition in the filmdeposition-alteration step is decreased (or the step time T1 of the filmdeposition-alteration step is shortened), the step time of thealteration step T2 is lengthened, or the total step time (T1+T2) isdecreased thereby to decrease a thickness of the reaction production percycle, the degree of alteration is increased. As described later, thethin film having film properties comparative to those of thermal siliconoxide can be obtained.

If only the film deposition-alteration step is carried out without thealteration step (namely, the film deposition process and the alterationprocess are carried out per rotation of the turntable 2), a layer(s) ofthe reaction product is formed and altered, and another layer (s) of thereaction product is formed and altered on the previous layer(s) of thereaction product, and these procedures are repeated. In this case,because only the extremely thin layer can be altered by the plasma, thealteration insufficiently takes place. Therefore, the layer(s) of thereaction product that is insufficiently altered is formed repeatedly. Asa result, only the thin film having insufficiently improved filmproperties can be obtained. On the other hand, when the previous layers)of the reaction product is altered before a subsequent layer(s) of thereaction product is formed on the previous layer(s) of the reactionproduct, the alteration can sufficiently take place even when the waferW passes through the alteration area 150 in a short period of time.Therefore, the thin film having improved and uniform film properties canbe obtained according to this embodiment of the present invention.

When trying to sufficiently alter the reaction product that may beobtained in various process recipes, or to enlarge a process window thatenables sufficient alteration, the high frequency electric powersupplied to the plasma generation member 80 from the high frequencyelectric power source 224 may be increased, or the plasma generationmember 80 is arranged closer to the turntable 2, or many of the plasmageneration members 80 are provided in order to enlarge the alterationarea 150.

However, the degree of the alteration is adjusted only by changing asequence of the process cycles, without changing the configurations ofthe film deposition apparatus, according to an embodiment of the presentinvention. In other words, a greater process window may be realizedwithout making the film deposition apparatus complex.

In addition, because the O₃ gas flow rates are not changed between thefilm deposition-alteration step and the alteration step, the pressureinside the vacuum chamber 1 is less likely to vary. Therefore, gasturbulence or damage (breakage) incurred on the members in the vacuumchamber 1 are avoided. Incidentally, when the pressure inside the vacuumchamber 1 is not significantly changed so that the gas turbulence doesnot take place, the O₃ gas is not necessary in the alteration step.Alternatively, when the supplying the O₃ gas is terminated, a flow rateof the separation gas may be increased by the flow rate of the O₃ gas,in order to keep the pressure inside the vacuum chamber 1 substantiallyunchanged.

In addition, because the film deposition-alteration step and thealteration step are switched from one to the other (in other words,supplying the Si containing gas starts and is terminated) after theturntable 2 rotates n times (n: integer), as shown in FIG. 10, it isrelatively easy to control the film thickness of the reaction productand to control the timing of the switching. Incidentally, the filmdeposition-alteration step and the alteration step may be switched fromone to the other after the turntable 1 rotates less than one rotation,which may make variations of the film properties and film thicknessuniformity because the wafers W on the turntable 2 are exposed todifferent gases or plasma at different timings in this case. However,because the process cycle is repeated plural times, the film propertiesand film thickness uniformity across the wafer W and between the wafersW are made uniform. Preferably, the switching timing may be controlledso that each of the wafers W is exposed to all the gases and the plasmathe same number of times. For example, it is preferable that each of thewafers W on the turntable 2 can be exposed to the Si containing gas thesame number of times.

Moreover, in the film deposition-alteration step, the alteration processis carried out with respect to the wafer W when the wafer W moves alongthe way from the second process area P2 to the first process area P1 inthe vacuum chamber 1 every time after the film deposition process, insuch a manner that the film deposition is not influenced by thealteration process. In addition, because the alteration process iscarried out every time after the film deposition process in the filmdeposition-alteration step, the thin film can be altered in a shortertime compared to a case where the thin film is altered after the filmdeposition is completed.

In addition, because the cover body 221 can impede the gas flowingtoward the activated gas injector 220 from the upstream side fromentering the inside of the cover body 221, an additional separation areaD does not need to be provided between the reaction gas nozzle 32 andthe activated gas injector 220. Therefore, production costs of the filmdeposition apparatus can be reduced. In addition, a by-product such asNO_(x) is less likely to be produced, so that the members thatconstitute the vacuum chamber 1 are less likely to be corroded.Moreover, because the cover body 12 is made of an insulating material,the cover body 221 is arranged closer to the plasma generation member80, so that the film deposition apparatus may be compact.

The reaction gases that may be used in the film deposition of siliconoxide according to an embodiment of the present invention are a bis(tertiary-butylamino) silane (BTBAS) gas, dichlorosilane (DCS),hexachlorodisilane (HCD), tris(dimethyl amino) silane (3DMAS),monoamino-silane, or the like. In addition, Trimethyl Aluminum (TMA),tetrakis-ethyl-methyl-amino-zirconium (TEMAZ),tetrakis-ethyl-methyl-amino-hafnium (TEMAH), bis (tetra methylheptandionate) strontium (Sr(THD)₂), (methyl-pentadionate)(bis-tetra-methyl-heptandionate) titanium (Ti (MPD) (THD)),monoamino-silane, or the like may be used as the first reaction gas, sothat an aluminum oxide film, a zirconium oxide film, a hafnium oxidefilm, a strontium oxide film, a titanium oxide film or the like may bedeposited, respectively. Moreover, as the second reaction gas thatoxidizes the above reaction gases, moisture vapor may be used instead ofthe O₃ gas. Furthermore, when obtaining a TiN film according to anembodiment of the present invention, where the oxidization gas is notused, a nitrogen containing gas such as ammonia (NH3) gas may be used asthe second reaction gas supplied from the reaction gas nozzle 32 and thealteration gas supplied from the gas introduction nozzle 34.

In addition, while a case where the two reaction gases are used to formthe reaction product is explained in the above examples, the presentinvention may be applied to a case where more than two reaction gases,for example, three or four reaction gases may be used to form a reactionproduct.

In addition, while the pair of the plasma generation members 80, 80 isprovided in the above embodiment, two or more (e.g., three) pairs of theplasma generation members 80, 80 may be provided in other embodiments.Alternatively, only one plasma processing member 80, which includes thepair of the electrodes 36 a, 36 b, may be provided.

While the turntable 2 is rotated with respect to the gas supplyingmembers (the nozzles 31, 32, 41, 42, and the plasma generation member80) in each of the above examples, the gas supplying members may berotated with respect to the turntable 2.

EXAMPLES

Next, experiments carried out to confirm an advantage of an embodimentof the present invention and the results are explained. Specifically,the experiments were carried out in order to investigate how the filmproperties are changed by the alteration step carried out in addition tothe film deposition-alteration step, when the silicon oxide film isdeposited. In addition, the step time ratios (T1:T2) were changed aslisted in the following table in the experiments. Incidentally, the steptimes T1, T2 are listed in the table.

TABLE step time ratio step time T1 step time T2 (T1:T2) (second)(second) Example 1 1:2 6 12 Example 2 1:3 6 18

The film properties of the films obtained in the experiments wereevaluated by applying a negative bias to the films and measuring aleakage current depending on the negative bias. In this evaluation, alower leakage current indicates that the film becomes more densified andcontains less of the impurities. Incidentally, the rotational speed was20 rpm and other conditions are the same throughout the experiments.

FIG. 12 is a graph illustrating the experiment results, which alsoillustrates results of a film obtained by carrying out only the filmdeposition-alteration step without the alteration step, a film obtainedby carrying out only the film deposition process without any alterationprocesses, and a thermal silicon oxide film, as reference examples.

As shown in FIG. 12, by carrying out the alteration step along with thefilm deposition-alteration step, the film properties are improvedcompared to the case where the alteration step is not carried out andthe case where no alteration processes are carried out. Especially, whenthe step time ratio T1/T2 is set to be 1/3, it is found that the filmhaving excellent properties, which are comparable with those of thethermal silicon oxide, is obtained.

While the present invention has been described in reference to theforegoing embodiments, the present invention is not limited to thedisclosed embodiments, but may be modified or altered within the scopeof the accompanying claims.

What is claimed s:
 1. A film deposition method, comprising: placing asubstrate in a substrate receiving portion of a table provided in avacuum chamber; and performing, at least once, a filmdeposition-alteration step and an alteration step, wherein within thefilm deposition-alteration step, an adsorption step of allowing a firstreaction gas to be adsorbed on an upper surface of the substrate, areaction product production step of allowing a second reaction gas andthe first reaction gas adsorbed on the upper surface of the substrate toreact each other, thereby producing a reaction product, and analteration process of allowing the upper surface of the substrate to beexposed to plasma into which an alteration gas is activated areperformed in this order by rotating a table with a rotation mechanismrelative to a first reaction gas supplying portion, a second reactiongas supplying portion, and a plasma generation portion, wherein thefirst reaction gas is supplied from the first reaction gas supplyingportion, the second reaction gas is supplied from the second reactiongas supplying portion, and the alteration is supplied from the plasma,wherein within the alteration step, the alteration gas activated by theplasma is supplied to the substrate in the substrate receiving areawhile the table is rotated, and the first reaction gas is not supplied,and wherein the second reaction gas is supplied to the vacuum chamber atthe same flow rate between the film deposition-alteration step and thealteration step, in order to maintain the inside of the vacuum chamberat substantially an equal pressure between the filmdeposition-alteration step and the alteration step.
 2. The filmdeposition method of claim 1, further comprising: repeating the filmdeposition-alteration step and the alteration step plural times, andswitching the film deposition-alteration step and the alteration stepwhen the table is rotated n times, n being an integer.
 3. The filmdeposition method of claim 1, wherein the alteration gas is at least oneof a noble gas and oxygen gas.